package org.apache.maven.plugin.internal;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.collection.DependencyCollectionContext;
import org.eclipse.aether.collection.DependencySelector;
import org.eclipse.aether.graph.Dependency;

/**
 * Assists in detecting wagon providers brought into the plugin class path via legacy Maven core
 * artifacts (e.g. maven-core:2.0.6) and excluding them. A plugin should be able to explicitly
 * declare dependencies on specific wagons for its use. However, the (old) wagons pulled in
 * transitively via legacy Maven core artifacts are usually not intended as dependencies and more
 * importantly screw up artifact resolution because they would get preferred over the core wagon
 * versions. This is a hack to provide backward-compat with Maven 2 (MNG-4528, MNG-4561).
 * 
 * @author Benjamin Bentmann
 */
class WagonExcluder implements DependencySelector {

  private final boolean coreArtifact;

  public WagonExcluder() {
    this(false);
  }

  private WagonExcluder(boolean coreArtifact) {
    this.coreArtifact = coreArtifact;
  }

  public boolean selectDependency(Dependency dependency) {
    return !coreArtifact || !isWagonProvider(dependency.getArtifact());
  }

  public DependencySelector deriveChildSelector(DependencyCollectionContext context) {
    if (coreArtifact || !isLegacyCoreArtifact(context.getDependency().getArtifact())) {
      return this;
    } else {
      return new WagonExcluder(true);
    }
  }

  private boolean isLegacyCoreArtifact(Artifact artifact) {
    String version = artifact.getVersion();
    return version != null && version.startsWith("2.") && artifact.getArtifactId().startsWith("maven-")
        && artifact.getGroupId().equals("org.apache.maven");
  }

  private boolean isWagonProvider(Artifact artifact) {
    if ("org.apache.maven.wagon".equals(artifact.getGroupId())) {
      return artifact.getArtifactId().startsWith("wagon-");
    }
    return false;
  }

  @Override
  public boolean equals(Object obj) {
    if (obj == this) {
      return true;
    } else if (obj == null || !getClass().equals(obj.getClass())) {
      return false;
    }

    WagonExcluder that = (WagonExcluder) obj;
    return coreArtifact == that.coreArtifact;
  }

  @Override
  public int hashCode() {
    int hash = getClass().hashCode();
    hash = hash * 31 + (coreArtifact ? 1 : 0);
    return hash;
  }

}
